WASHINGTON -- North Korea vowed Monday to continue its pursuit of nuclear missiles in the wake of the United States' rare deployment of three aircraft carrier groups near the Korean Peninsula.

In a letter addressed to UN Secretary-General Antonio Guterres, Ja Song-nam, Pyongyang's top envoy to the UN, said the carrier groups' joint exercises with South Korea were creating "the worst ever situation" in the region, according to foreign news reports.

"The large-scale nuclear war exercises and blackmails, which the US staged for a whole year without a break in collaboration with its followers to stifle our republic, make one conclude that the option we have taken was the right one and we should go along the way to the last," he was quoted as saying.

(Yonhap)

North Korea has repeatedly said it will develop its weapons capability until it can strike the mainland US with a nuclear missile. In July, the communist regime tested two long-range missiles and followed up with its sixth and most powerful nuclear detonation in September.

Ja also protested recent overflights of US bombers near the Korean Peninsula.

The four-day naval exercises kicked off Saturday as US President Donald Trump traveled through the region to drum up further support toward ending Pyongyang's nuclear program.

It was the first time since 2007 that three US carrier strike groups operated together in the region.

Ja accused the UN Security Council of "turning a blind eye to the nuclear war exercises of the United States, who is hell bent on bringing a catastrophic disaster to humanity," according to the reports.

He also asked Guterres to circulate the letter to the council and the General Assembly. (Yonhap)